Ethereum developers implemented the network’s first-ever “shadow fork” on Monday, marking an important milestone in the ongoing shift to a proof-of-stake (PoS) consensus. 

The shadow fork provides a venue for developers to stress test their assumptions around the network’s complex shift to PoS, according to Ethereum Foundation developer Parithosh Jayanthi. “The aim of the Kiln merge testnet was to allow the community to practice running their nodes, deploying contracts, testing infrastructure, etc.,” he tweeted on Sunday.

Wondering what the #TestingTheMerge team has been up to?

The aim of the Kiln merge testnet was to allow the community to practice running their nodes, deploying contracts, testing infrastructure, etc. We hope it’s helping the community get a sense of the post merge world!

— parithosh | (@parithosh_j) April 10, 2022

Kiln refers to the last testnet of the so-called merge, which involves transitioning Ethereum’s Execution Layer from proof-of-work to PoS. In a March 14 blog post, the Ethereum Foundation described the merge as a “culmination of six years of research and development” intended to make the network more secure and energy-efficient. 

Ethereum Foundation developer Marius van der Wijden confirmed on Monday that PoS testing was underway. “Today will be the first mainnet shadow fork ever. We’re roughly 690 blocks (~2 h) away from TTD,” he tweeted.

We’re very close to a historical event. We’re testing PoS on #Ethereum. Today will be the first mainnet shadow fork ever. We’re roughly 690 blocks (~2 h) away from TTD. Follow here: https://t.co/T20ZMgApYw or https://t.co/Uod8WBsqtw
Huge props to @parithosh_j! #TestingTheMerge pic.twitter.com/M8ZcHnKqaL

— MariusVanDerWijden (@vdWijden) April 11, 2022

Positive developments surrounding the merge have fed an increasingly bullish narrative for Ethereum — one that allowed the Ether (ETH) price to temporarily break a months-long downtrend. While ETH and the broader crypto market are recoiling in a new bout of risk aversion, the prospect of earning passive rewards on the Ethereum network has attracted considerable interest from investors.

Related: Ethereum hash rate scores new ATH as PoS migration underway

The number of staked ETH on Ethereum’s Beacon Chain is fast approaching 10.9 billion, with the average balance currently 33.5 ETH, according to industry data. Beacon Chain currently has over 340,000 validators, which represents a gain of 13% from early March when the 300,000th validator was first recorded.